Electric burglar-alarm.



Nu. 632,5l2. Patented Sept. 5, I899. C. COLEMAN.

ELECTRIC BUBGLAB ALARM.

(Application filed Sept. 28, 1896.)

4 Sheets-Sheet (No Model.)

No. 632,512. Patented Sept. 5, I899.

c. COLEMAN. ELECTRIC BURGLAR ALARM.

(Application flled Sept. 28, 1896.)

' 4 Sheets-Sheet 2,

(No Model.)

No. 632,5l2. Patented Sept. 5, I899.

' c. COLEMAN.

ELECTRIC BUBGLAB ALARM.

(Application filed Sept. 28, 1898.)

4 Sheets8hset 3.

(No Model.)

rm: recu s PETERS co. wnuroumoj. wasnmsrou. n. c.

Patented Sept. 5, I899.

C. COLEMAN. ELECTRIC BUBGLAB ALARM.

(Application filed Sept. '28, 1896.\

4 Sheets-Sheet 4..

(No Model.)

. THE ncnqls fiETEflS co. PHOTULITHQ, wnsnmmu. u. c

UNITED STATES- PATENT OFFICE.

CLYDE COLEMAN, OF CHICAGO, ILLINOIS, ASSIGl OR, BY MESNE ASSIGN- MENTS,OF TWO-THIRDS TO THE BANKERS ELECTRIC PROTECTIVE COMPANY OF SAME PLACE.

ELECTRIC BuReLAR-ALARM.

SPECIFICATION formingpart of LetterslPatent No. 632,512, dated September5, 1899.

' A li n fii lt Septmber28,1896. Serial no; 607,129. (No model.)

To aZZ whom it may concern.-

Be it known that L'OLYDE COLEMAN, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in ElectricalBurglar-Alarms and in Rheostats for use in Burglar-Alarm and otherElectrical Systems, of which the following is a specification.

The present invention relates in part to an electrical burglar-alarmsystem of that class in which there is a local alarm-circuit which iscontrolled by a circuit herein called the main or controlling circuit,and a device so related to said circuits that it is influenced bycertain variations in the electrical condition of the main circuit,andwhen so influenced will give a signal or cause one to be given. Moreparticularly stated, this part of the invention relates to that'class ofburglar-alarm systems in which the amount ofresistance in the maincircuit, considered in its entirety,

remains constant, while the resistance in lo-' vice which is so relatedto the main and sig-.

nal circuits as to be controlled by the one and control the other as ameter; but the invention is not limited to a meter strictlyso-called,this term as used in this specification being intended tocomprehend any device that will be influenced by a variation in theresistance of the main circuit or a variation in the voltage or amperageof the current in the main circuit and when soinfluenced will give asignal or cause one to be given. The

term station as used in this specification is intended to comprehend anyplace where it is desired to give a signal when the system is tamperedwith. The term guarded structure is intended to comprehend a safe, abuilding, or any part of a building or other structure or inclosurewhich it is desired to guard. any device, of whatever construction, foropening and closing a' circuit or for diverting a current from onecircuit or part thereof to another.

used for resisting the'current. The term rheostat comprehends theapparatus or mechanismincluding a resistance or resistances by which theamount of resistance in circuit is varied either by an increase ordecrease. B y combination-rheostat is meant a rheostat having aplurality of different resistances and means whereby they may bearranged in many different orders or combinations, or, in other words,permutated, in one sense of the term. The term reciprocating rheostatsmeans a plurality of rheostats or mechanisms, of whatever construction,one of which increases and the other of which decreases the amount ofresistan cc in circuit, the increase and decrease being alike in amount,so that while the resistance in local portions of the circuit is variedthe total resistance in the entire circuit remains constant.

The invention consists in the features of novelty that are particularlypointed out in the claims hereinafter, and in order that it may be fullyunderstood I will describe it with reference to the accompanyingdrawings, which are made a part of this specification, and in which-Figure 1 is a diagram of a burglar-alarm system embodying the invention.Figs. 2 and 3 are respectively a side elevation and a plan view of arheostat constructed in accordance with the invention. Fig. 4 is ahorizontal section of a portion thereof. are views showing, partly inelevation and partly in diagram, rheostats constructed in accordancewith the invention, Fig. 5 showing the rheostat that is located at theguarded structure, and Fig. 6 the rheostat that is located at thestation, when said rheostats are embodied in a burglar-alarm embodyingthe invention.

A represents the device herein termed a Figs. 5 and 6 The term switchcomprehends The term resistance comprehends a coil or a part of a coilor other device meter. It is so constructed and connected with the mainor controlling circuit that upon a variation in the current in saidcircuit it will close an alarm-circuit or in some other way cause anaudible or visible signal to be given. In the drawings I have shown analarm mechanism consisting of a magneto-electric bell B, operated by abattery C; but any other form of alarm mechanism or signaling devicemay, if desired, be used. As shown, the alarm=circuit comprises theneedle a or some other part of the meter, two contact screws or pointsc, which are located upon opposite sides of the needle a and in the pathtraveled thereby when in motion, two wires 0 0, connected with thescrews 0 0, respectively, a wire 0 leading therefrom to one pole of thebattery, awire C leading from the other pole of the battery'andterminating in a contact 0 a switch C constituting or carried by thearmature of an electromagnet in the manner and for thepurposehereinafter described, a wire 0 leading therefrom to one of thebinding-posts of the bell B, and a wire O leading from the otherbinding-post of the bell back to the needle of the meter.

When the current in the main or controlling circuit is normal, the meteris balanced with its needle in central position between the two contactsdo" and out of contact with either of them; but when the current isvaried either by an increase or a decrease the needle will be deflectedand come in contact with one or the other of said contacts 0' c",accordingly as the variation is by way of increase or decrease, andthereby close the alarm-circuit and cause an alarm to be sounded. Asbefore intimated, the invention is not limited to this particularmechanism for controlling the alarm-circuit; but, on the contrary, itcomprehends any device, of whatever construction, that will beinfluenced by a variation in the current reaching it over the maincircuit and when so influenced will cause an alarm to be given, it beingthe intention that the term meter as used in this specification shallcomprehend any such mechanism. Nor is the invention limited to an alarmmechanism of the construction shown and described, any visual or audiblealarm mechanism or signaling device that can be controlled bya meterwithin the meaning of this term as hereinafter used being within thescope of the invention; The needle of the meter may, if desired, berelied upon as a visible signal.

D is the battery of the main or controlling circuit,which circuitconsists ofawire D,leading from one pole of the battery, a switch Dcarried bythe armature C ,a wire D ,terminating at one end in a contact61 located in operative proximity to the switch D whence said wireextends to the guarded structure, where it is connected with one of thebindingposts of a rheostat E, located at the guarded structure, a wire Dleading from the other binding-post of said rheostat to one of thebinding-posts of a rheostat 6, located at the station, a wire D leadingfrom the otherbinding-post of the rheostat e to one of the bindingpostsof the meter A, and a wire D leading from the other binding-post of themeter back to the other pole of the battery. Each of the rheostats,considered alone, permutes in the sense that a given nu mber'ofresistances may be arranged or combined in a greater number of orders orcombinations, and the rheostats at the station and guarded structure,considered together, permute in the sense that their action isreciprocal, each complementing the other-that is to say, each of them iscapable of both throwing in and throwing out resistance; but theirconstruction and arrangement are such that the action of one complementsthe action of the other. If one throws resistance in the other throws itout, and vice versa, and these variations, which are alike in amount,are accomplished simultaneously, or

practically so. The rheostats are operated by electromagnets Ff, locatedon what is herein called the switching circuit and supplied with currentfrom a battery G, located at the station. The switchingcircuit isnormally open and is made up of a wire G, leading from one pole of thebattery G to the magnet F, a wire Gileading from said magnet to theswitch D a wire G terminating in a contact g ,located in operativeproximity to the switch D whence said wire extends to the other pole ofthe battery, and a wire G, bridging the wires Gr and G on which wire Gthe magnetf is located.

The switch D is common to both the main circuit and theswitching-circuit, and as a result of this when the switch is inposition to close the switching-circuit it leaves the main circuit open,the main circuit being normally closed. By using such a switch common toboth circuits I am enabled to use between the station and the guardedstructure one and the same wire as a part of both circuits, and at thesame time it provides means for opening the main circuit and holding itopen during the intervals during which the switching-circuit is closedand'the changing of the resistance in the main circuit is taking place.If the main circuit were left closed while the resistance is beingchanged,.there would bea disturbance of the meter that would cause analarm to be given. It is true that alarms that would be produced in thisway would have character istics that would enable the attendant todistinguish them from alarms caused by surreptitious meddling with thesystem; but stilllprefer to avoid the giving of any alarms exceptingwhen the system is tampered with, and hence I provide means for makingthe main circuitinoperative while changes in the resistance produced bythe normal operation of the system are taking place.

It will be seen that the magnets F and f are arranged in multiple, andthis is preferred for the following reasons: If the main and theswitching circuits were entirely separate and independent throughout andthe magnets F andf were arranged in series, the system could becrippled, so as to prevent it from producing any variations in theresistance, by simply cutting the switching-circuit at any one point.This done, it would be possible to ascertain the amount of resistance incircuit at the guarded structure and short-circuit the guarded structureby an instrument having alike resistance, and the system would therebybe rendered useless; but by arranging the magnets F andfin multiple,even if the switching-circuit were entirely independ ent of the maincircuit, the system could not be crippled in the manner described, forthe reason that access cannot be had to that portion of theswitching-circuit upon which the magnetfis arranged, and consequently,even though the magnet F be cut out of circuit, each time theswitching-circuit is closed the magnet f will operate the rheostat e andchange the resistance at the station, and in the absence of acorresponding change at the guarded structure an alarm would be given.The only way to avoid this would be to put in circuit at the point wherethe guarded structure is short-circnited a rheostat constructed andarranged to operate precisely like the rheostat at the guardedstructure; bntin view of the complicated construction of this rheostat,the great number of its combinations, the facility with which the orderof its combinations may be rearranged from time to time, and the factthat the arrangement of its combinations will be kept a secret, thiswould be next to impossible. The same result would follow if the magnetsF and f were located upon circuits that are entirely separate. A furtherprotection to the switching-circuit is had by using one and the samewire for a portion of it and a portion of the main circuit.

If desired, the switch D may be operated manually but I prefer tooperate it by an electrical appliance which is controlled by achronometer H or other time mechanism. Preferably this applianceconsists of an electromagnet H, arranged in operative relation to thearmature G a wire H which leads from said magnet to a ring H having init a number of holes or perforations h for receiving a number of pins orcontacts H, a switch 11 operated by the chronometer, a wire H leadingfrom the switch to one pole of the battery 0, (whichis common to boththe alarmcircuit and the chronometer-circuit,) and a wire H leading fromthe other pole of the battery back to the magnet H. Separate batteriesmay, if desired, be used for these two circuits; but since thealarm-circuit seldom needs any current I prefer to use one battery forboth of them. By including the armature O or a part carried thereby inthe alarm-circuit and using this armature or part as a switch thealarm-circuit is opened at 0 each time the chronometer-circuit is closedand the armature C attracted. A pin H may be placed in each of theperforations 71 if de- 13, located in the field of the magnet F.

sired, so that the changes will be made at regular intervals; but Iprefer to leave the pins out of some of the perforations, so that thechanges will be made at irregular intervals.

Coming now to the rheostats themselves, it may be stated that they areof similar construction, the only difference between them being thattheir contact-points are so connected with the resistances that as theswitches reach said contact-points in succession resistance willbethrown in at one of the rheostats and out at the other, the variationat the two rheostats being alike in amount at any given operation,although the variations at successive operations may be different inamount and evenin characterthat is to say, at any given simultaneousoperation of the two rheostats the variation is alikein amount, althoughit is by way of an increase in the resistance at one of them and adecrease at the other. At the next succeeding operation the amount ofthe variation at either of the instruments maybe the same or more orless than it was at the preceding operation, but still alike in amountat the two rheostats. In other words, at any given operation thevariation may be by way of an increase in the resistance in the rheostatat the guarded structure and a corresponding decrease in the resistancein the rheostat at the station, and at the next operation the variationmay be by way of a decrease in the resistance in the rheostat at theguarded structure and a corresponding increase in the resistance in therheostat at the station.

For the sake of brevity and clearness the following description will beconfined to the rheostat which is located at the guarded structure,excepting when it becomes necessary to refer to the onelocated at thestation, and similar parts of both will be indicated by similarreference letters and numerals, the prime-mark being added to thereference letters and numerals used to indicate the parts of therheostat located at the station.

Upon abase 1 is built a box 2, to one of the sides 3 of which aresecured blocks 4, to which latter is seen red a bar extending parallelwith the side 3 of the box. In this side of the box and in the bar 5 arejournaled a train of intermeshing differential gear-wheels 6, 7, and 8.The first wheel of the train .has formed upon or secured to it aratchet-wheel 9, en-' gaged by a dog 10, which is pivoted to one end ofa lever l1,thatis fulcru medjto a bracket 12 and carries at its otherend an armature The dog 10 is held normally in engagement with theratchet-wheel by a spring 14, which is secured to the lever and bearsagainst the heel of the dog. When the armature 13 is attracted by themagnet F, the dog 10, being in engagement with the ratchet-wheel 9,turns the train of gear-wheels each in the direction of the arrow placedupon it, the movement of the entire train at each operation of the dogICO being limited to the number of degrees which are embraced betweenradial planes cutting two adjacent teeth of the ratchet-wheel by astop-dog 15, which is carried by the lever 11 and engages the teeth ofthe first gear-wheel 6 of the train, the number of teeth on this wheelbeing the same as the number of teeth on the ratchet-Wheel. Twenty areshown in the drawings; but, if desired, a'greater or less number may beused without in any way departing from the spirit of the invention. whenthe magnet F is denergized, a spring 16, engaging the lever 11,withdraws the armature and withdraws the dogs 10 and 15. The retrogrademovement of the train of gear-wheels is prevented bya spring-dog 17,which is secured to the bar 5 and engages the teeth of theratchet-wheeli).

Arranged concentrically with the axis of the wheel 6 isa group of pinsorcontacts 18, which do not have contact with the wheel and arecompletely insulated from eachother. Preferably this is accomplished bymaking the side 3 of the box of hard rubber or other insulating material(if desired, the entire box and its base may be constructed of the samematerial) and firmly setting the pins in perforations formed in it. Thepins are disposed at equal distances apart and correspond in number withthe teeth on the ratchet-wheel 9. Each of them is connected with one oranother of six wires, numbered 19 to 2%, inclusive. The wire 19 isconnected directly with the wire D of the main circuit, which latteralso connects with one end of a resistancecoil 25, and the wiresnumbered 20 to 2%, inclusive, are connected with said coil atsuccessively-greater distances from the end with which the wires D and19 connect. This single coil 25, tapped in this manner, may beconsidered as a single resistance tapped at different points; but Iprefer to consider it as a group of resistances the lesser of which areincluded in the greater. In other words, I prefer to consider thatportion of the coil which is included between the wires D and 20 as oneresistance, that portion which is included between the wires D and 21another resistance, which includes or is in part made up of the firstresistance, and so on, the

entire coil being the greatest one of the groupand including all of theothers. Hence the term resistance (singular) as used in thisspecification must be understood as meaning so much of the coil 25 as isincluded between the wire D and any one of the wires 20, 21, 22, 23, or24: and disregarding all other of said wires, and the term group ofresistances must be understood as meaning two or more of suchresistances; but I desire to have it understood that in its broadestaspect the invention so far as it includes a group of resistances is notlimited to this arrangement, in. which the lesser are included in thegreater-i. e. in series-but, on the contrary, a group of resistances,each of which comes in contact with them in succession as the wheel isrotated.

Arranged concentrically with the axis of the wheel 7 is a group ofequidistant insulated contact-pins 180, the number of pins used in thisgroup being different from the number used in the group alreadydescribed. In the drawings I have shown nineteen; but this is anarbitrary selection, and any other number, excepting the exact numberused in the group 18, may be used. The accomplishment of the objects ofthe invention necessitates differential groups of contact-points -'i.6., groups no two of which contain the same number-and such anarrangement of mechanism that the switches of the several groups advanceat each operation from one to another of the contactpoints insuccession. hat I regard as the simplest and best way to accomplish thisis to mount the'switches on differential gear-wheels and to make the differentials of the several gear-wheels and the several groups of contactsagree. To be more explicit, in one group I have used twenty contacts andhave provided means for moving the switch of this group throughone-twentieth of a revolution at each operation, and in the other groupI have used nineteen contacts and have provided means for moving theswitch of this group of contacts through one-nineteenth of a revolutionat each operation, so that each time the switch 26 advances from onecontact to the next in the group 18 the switch 260, carried by the wheel7, ad-

vances from one to the next contact of the group 180. The switch'260 isinsulated from the wheel 7 by being secured to a block 27 of insulatingmaterial, which block is in turn secured to the wheel. Each of thecontactpins 180 is connected with one or another of six wires numbered,respectively, 190 200 210 220 230 2&0. The wire 190 is connecteddirectly with the wire D of the main circuit, which latter is alsoconnected directly with one end of a resistance-coil 250, (like the coil25,) and the wires 200, &c. are connected with said coil atsuccessivelygreater distances from the end with which the wires D and190 connect. The switch 260 has a heel portion 29, which constitutes abrush and has contact with an insulated metallic ring 30, which issecured to the side 3 of the box. Arranged concentrically with the axisof the wheel 8 is a group of equidistant insulated contact-pins 181, thenumber of pins used in this group (thirteen being shown) being differentfrom the number used in either of the other groups.

What has already been said about the differential arrangement of thepins of the two groups already described is here applicable.

Each of these pins is connected with one or another of four wires 191,201, 211, ,and 221. The wire 191 is connected directly with one end of aresistance-coil 251 (like the coil 25) and a wire 31, the latter wirebeing also connected with said coil and with the ring 30. The wires 201,211, and 221 are connected with the resistance-coil 251 atsuccessively-greater distances from the end with which the wires i fromthe main circuit over the wire D is as follows: From the wire D to thecoil 25, over the coil 25 to the point of connection with the wire 23,over the wire 23 to the pin 18, from this pin to the switch 26, throughthe switch to the wheel 6, thence to the wheel 8 either through thewheel 7 or through the metallic bar 5, which is diagrammaticallyrepresented in Fig. 5 by a dotted line, from the wheel 8 to the switch261, through the switch to the contactpin 181, with which it is incontact, thence to the wire 221, through said wire to the extremity ofthe coil 251, thence through the entire coil to the wire 31, throughsaid wire to the ring 30, from the ring 30 to the brush 29, through thebrush to the switch 260, through the switch to the contact-pin 180,withwhich it is in contact, thence to the wire 200, through said wire to thecoil 250, through said coil from the point at which the wire 200connects to the wire D of the main circuit, and through said wire to therheostat c at the station. For the purpose of this description let it beassumed that each of the coils 25 and 250 represents a total resistanceof one thousand ohms an d the coil 251 five hundred ohms, that the coil25 is tapped by the wires numbered 20 to 24, inclusive, at pointsrepresent ing resistances of one hundred, three hundred, five hundredseven hundred, and one thousand ohms, respectively, and so with the coil250, and that the coil 251 is tapped by the wires 201, 211, and 221 atpoints representing resistances of one hundred, threehundred, and fivehundred ohms, respectively. \Vith the parts in the positions shown inthe drawings the total resistance in circuit at this rheostat E, whichis located at the guarded structure, will be fifteen hundred ohms. hen,however, the magnet F is energized, each of the switches 26, 260, and261 will be advanced to the next contact-point of its group, and whenthis takes place the total resistance in circuit at this rheostat willbe only four hundred ohms. At the next change produced by the operationof the magnet F it will be two thousand ohms, at the next six hundred,at the next one thousand, at the next eleven hundred, at the next twelvehundred, at the next twelve hundred, at the next four hundred, the] Thusit will be seen the variations are by way of both increase and decrease,and by an accident of theconstruction shown the seventh operation of therheostat will not produce any variation whatever in the resistance.WVhatever be the action of this rheostat at the guarded structure, therheost-at at the station will complement it, so that while theresistance in local portions of the main circuitis constantly changingthe resistance in the entire circuit remains constant. It is because ofthis reciprocal action of the two rheosta-ts that they are herein termedpermutating rheostats.

The sum of all the contacts in the three groups described is fifty-two.If these fiftyvtwo contacts were all arranged in a single group and asingle switch were used each complete cycle of operations of the instrument would produce fifty-two changes in the resistance, after which thesame fifty-two changes would be repeated by each succeeding completecycle of operations; but by arranging the contacts in a plurality ofgroups and using aplurality of switches the changes are permuted, sothat with this same number of contacts, disposed as shown in thedrawings, each complete cycle of operations of the instrument producesfour thousand nine hundred and forty changes. It is not meant by thisthat four thousand nine hundred and forty diiferent amounts ofresistance are included in the cycle, but that the cycle includes fourthousand nine hundred and forty changes, all of which must-be knownbefore the instrument can be defeated, which is just as effective as ifthere were four thousand nine hundred and forty different amounts ofresistance.

It will be seen that each resistance of each group has a plurality ofcontacts, all connected with it at the same point, and by this meanseach resistance is used repeatedly in each cycle of operations. It willbe seen also that in grouping the contacts the contacts of the severalresistances are not arranged in the same order or succession as theresistances themselves are-that is to say, they are not arranged so thatsuccessive changes shall be always by way of an increase or always byway of a decrease. On the contrary, they are arranged irregularly, sothat the changes shall vary irregularly from an increase to an increaseor an increase to a decrease or a decrease to a decrease or a decreaseto an increase, and this makes it more difficult for a meddler toanticipate the action of the system. It will be seen also that .theseveral contacts of each resistance are not adjacent to each other, butare separated by contacts of another resistance or other resistances,and here again irregularity is preferable to regularity.

Having thus described my invention, the following is what I claim as newtherein and desire to secure by Letters Patent:

1. In a burglar-alarm system, the combination with a main circuit andcircuit-varying devices at the station and guarded structurerespectively, of electrical appliances, including a switching-circuitextending to the guarded structure for operating the circuitvaryingdevice at the guarded structure, electrical appliances for operating thecircuitvarying device at the station, and means for causing an alarm tobe given .it' the normal condition of the switching-circuit extending tothe guarded structure is interfered with, substantially as set forth.

2. Ina burglar-alarm system, the combination with a main circuit andcircuit-varying devices arranged therein and located at the station andthe guarded structure respectively, of electrical appliances foroperating the circuit-varying devices, the appliance for operating thecircuit-varying device at' the station being arranged upon a circuitwhich is complete within the station, substantially as set forth.

3. In a burglar-alarm system, the combination with a main circuit andcircuit-varying devices arranged therein and located at the station andguarded structure respectively, of electrical appliances for operatingsaid circuit-varying devices, said electrical appliances includingelectromagnets arranged in multiple, substantially as set forth.

4. In an electrical burglar-alarm system, the combination with a maincircuit, circuitvarying devices arranged therein, 'a switching-circuit,and means arranged thereon for operating the circuitvarying devices, ofa switch common to and forming a part of both of said circuits, saidswitch being so disposed that when one of the circuits is open the otheris closed, substantially as set forth.

5. In an electrical burglar-alarm system, the combination of a normallyclosed main circuit, alarm mechanism controlled thereby, means forvarying the normal condition of the circuit, and a normally openswitching-circuit for operating said circuit-varying means,-

said circuits including a switch which is common to-both of them, of anautomatic device for operating said switch, said switch being sodisposed that when in one position the .main circuit is closed and theswitching-circuit is open and when in another position the main circuitis open and the switchingoircuit is closed, and means for rendering thealarm mechanism inoperative while the main circuit is open at saidswitch, substantially as set forth.

6. In an electrical burglar-alarm system, the combination of a maincircuit and a switching-circuit including a wire which 7. In anelectrical burglar-alarm system,

the combination of a main circuit, a switchingcircuit, said circuitsincluding a wire common to both of them, circuit-varying devicesarranged in the main circuit, electrical appliances arranged in theswitching-circuit for operating the circuit-varying devices, and aswitch common to both of said circuits so disposed that when one of themis open the other is closed, substantially as set forth.

8. In an electrical burglar-alarm system, the combination of a maincircuit, alarm mechanism controlled thereby, a switching-circuit, meansarranged upon the switching-circuit for varying the normal condition ofthe main circuit, a switch common to both of said circuits so disposedthat when one is closed the other is open, and automatically-operatingmeans for controlling said switch, substantially as set forth.

9. In an electrical burglar-alarm system, the combination with a maincircuit, circuitvarying devices arranged therein,a switchingcircuit,electrical appliances arranged therein for operating the circuit-varyingdevices, a switch common to both of said circuits so disposed that whenone is open the other is closed, an electrical appliance for operatingsaid switch and time mechanism for controlling as set'forth.

11. In an electrical burglar-alarm system, the combination of analarm-circuit, a meter for controlling it, a main circuit electricallyconnected with the meter, circuit-varying devices arranged in the maincircuit,a switchingcircuit, electrical appliances arranged in saidcircuit for operating the circuit-varying devices, a switch common toboth the main circuit and the switching-circuit, a chronometer,

a circuit having a switchoperated by the chronometer, a magnet arrangedin the chronometer switch-circuit, and an armature arranged in the fieldof the magnet and controlling the switch which is common to the main andswitching circuits, substantially as set forth.

12. In an electrical,burglar-alarm system, the combination of analarm-circuit having a switch which is normally closed, a normally openchronometer switching-circuit, a battery common to both of saidcircuits, and means arranged upon the chron ometerswitching-circuit foropening the switch of the alarm-circuit when the chronometerswitching-circuit is closed, substantially as set forth;

13. In an electrical burglar-alarm system, the combination of a maincircuit, a local alarm-circuit having a switch, a meter electricallyconnected with the main circuit and controlling a local alarm-circuit,aswitchingcircuit, including a part which is included also in the maincircuit, means arranged upon the switchingcircuit, for varying thenormal condition of the main circuit, means for opening the main circuitwhen the switching-circuit is closed and holding it open while theswitching-circuit is closed, and means for opening the switch of thealarm-circuit when the main circuit is opened as aforesaid,substantially as set forth.

14. In an electrical burglar-alarm system, the combination of a maincircuit, a switching-circuit, a switch common to both of themand sodisposed that it opens and closes them reciprocally, a localalarm-circuit having a switch, a chronometer switching-circuit, abattery common to the local alarm-circuit and thechron'ometerswitching-circuit, and means arranged upon the chronometerswitchingcircuit for simultaneously operating both of the switchesaforesaid so that the main and alarm circuits are simultaneously openedat their respective switches, substantially as set forth.

15. A rheostat having, in combination, a resistance, a movable contactmember, and means for bringing in circuit the same resistance atdifferent points in the movement of said cont-act member, substantiallyas set forth.

16. A rheostat having, in combination, a unitary resistance, a pluralityof contacts with which one and the same terminal of said resistance iselectrically connected, and a switch arranged in operative relation tosaid contacts, whereby said resistance is included in circuit atdifferent points throughout the movement of the switch, substantially asset forth.

17. A rheostat having, in combination, a plurality of resistances, aplurality of contacts electrically connected with one and the sameterminal of each of said resistances, and a switch arranged in operativerelation to said contacts, substantially as set forth.

18. A rheostat having, in combination, a plurality of resistanceselectrically connected in series, a contact electrically connected withthe terminal of each individual resistance, and a switch arranged inoperative relation to said contacts, the orderin which the contacts arearranged being different from that in which the resistances arearranged, substantially as set forth.

19. A rheostat having, in combination, a plurality of resistanceselectrically connected in series, a plurality of contacts electricallyconnected with one and the same terminal of each individual resistance,and a switch arranged in operative relation to said contacts, saidcontacts being arranged in irregular order, substantially as set forth.

20. A rheostat having, in combination, means for increasing the amountof resistance in circuit, means for decreasing the amount of resistancein circuit, and automatically-operatin g means for operating these two,resistance-changing means for irregularly varying the resistance incircuit, substantially as set forth.

21. A rheostat having, in combination, automatically-operating means forchanging the amount of the resistance in circuit-,and means forirregularly varying the amount of successive changes, substantially asset forth.

22. A rheostat having, in combination, means for increasing the' amountof resistance in circuit, means for decreasing the amount of resistancein circuit,automaticallyoperating means for irregularly operating thesetwo resistance-changing means, and means for irregularly varying theamount of successive changes, substantially as set forth.

23. A rheostat having in combination a plurality of resistances, aplurality of contacts common to each of said resistances, the contactsof one resistance being disposed between the contacts of anotherresistance, and a switch arranged in operative relation to saidcontacts, substantially as set forth.

2&. In a rheostat, the combination of a plurality of resistancesdiffering in amount, a plurality of contacts arranged in a series andelectrical connections between each of said resistances and one of thecontacts, the contacts corresponding with the resistances in the orderof their increase being irregularly disposed in the series so thatsuccessive contacts in the series. are not connected withsuccessively-increasin g resistances, substantially as set forth.

25. A rheostat having in combination a plurality of resistances, aplurality of contacts common to each of said resistances, wireselectrically connected with each of the resist ances and eachelectrically connected with a plurality of the contacts, all of saidcontacts being arranged in a single group, and a switch arranged inoperative relation to said contacts, substantially as set forth.

26. A rheostat having in combination a plurality of groups ofresistances, a number of contacts arranged in a plurality of separategroups, corresponding with the groups of resistances, Wires electricallyconnected with the resistances and each electrically connected with aplurality of the contacts in one of the groups, a plurality of switches,one for each group of contacts, and means for operating them,substantially as set forth.

27. A rheostat having, in combination, a plurality of resistances andmechanism for including various permutations or combinations of them incircuit, said mechanism being differential whereby the changes in eachcomplete cycle of operations may include all possible permutations orcombinations of the resistances, substantially as set forth.

28. A rheostat having, in combination, a

plurality of resistances, contacts arranged in forth.

29. A rheostat having, in combination, a

. plurality of resistances, contacts arranged in a plurality ofdifferential groups, a plurality of switches adapted to have contactwith the contacts of the several groups respectively, and difierentialmechanism whereby the relations of the several groups of contacts andtheir respective switches are changed so that at each operation thecombination of contacts included in circuit is changed and so that acomplete cycle of operations may in-v clude all possible permutations orcombinations of each contact of each group with every contact of anothergroup, substantially as set forth.

30. A rheostat having, in combination, a plurality of resistances,contacts arranged in a plurality of cyclic groups, and diiferentialmechanism for making contact in succession with the successive contactsof each group at each operation, whereby the changes in each completecycle of operation may include all possible permutations or combinationsof each contact of each group with every contact of another group,substantially as set forth. I Y

31. A rheostat having, in combination, a plurality of resistances,contacts arranged in a plurality of difierential cyclic groups, aplurality of switches arranged in operative relation to the contacts ofthe several groups respectively, and differential mechanism forsimultaneously moving all of said switches so that at each operationeach is advanced from one contact to another of its group, whereby theseveral switches complete their respective cycles of operations atdifierent periods and whereby each contact of each group is arranged inall possible combinations with every contact of another group,substantially as set forth.

32. A rheostat having, in combination, a

group of resistances, a group of contacts elec-.

trically connected therewith, a switch arranged in operative relation tosaid contacts, a second group of resistances, a second group of contactselectrically connected therewith, a second switch electrically connectedwith the first switch and arranged in operative relation to the secondgroup of contacts, the two groups of contacts being differential, and

differential mechanism for operating the switches whereby each contactof each group may be arranged in all possible combinations with everycontact of another group, substan- I tially as set forth.

In a rheostat, the combination of a plurality of resistances, contactselectrically connected therewith and arranged in a plurality ofdifierential groups, switches arranged in operative relation to saidcontacts, revoluble devices carrying said switches and differentialmechanism for revolving said devices whereby each contact of each groupmay be arranged in all possible combinations with every contact ofanother group, substantially as set forth.

34:. A rheostat having in combination a plurality of groups ofresistances said groups being arranged in series, a number of contactsarranged in a plurality of differential groups, wires electricallyconnecting the contacts with the resistances, a plurality of switchesarranged in operative relation to the contacts, a plurality of wheelscarrying the switches and having differential gearing, and means foroperating the wheels, substantially as set forth.

35. A rheostat having in combination a group of resistances, a pluralityof wires leading therefrom, a group of contacts with which said wiresare electrically connected, a switch arranged in operative relation tosaid contacts, a wheel by which said switch is carried, a second wheel,asecond switch carried by the second wheel, means electrically connectingthe first and second switches, a second group of contacts arranged inoperative relation to the second switch, a plurality of wireselectrically connected with said contacts, a second group of resistanceswith which said wires connect, a wire leading from the second group ofresistances, a third switch with which said wire is electricallyconnected, a third wheel by which said switch is carried, a third groupof contacts arranged in operative relation to said switch, a number ofwires electrically connected with said contacts, and a third group ofresistances with which said wires are connected, the contacts beingarranged in differential groups, substantially as set forth.

CLYDE COLEMAN.

Witnesses:

L. M. HOPKINS, N. O. GRIDLEY.

